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The large families of the molecules of life are at the origin of the discovery of new compounds with which to treat disease. The arrival of artificial intelligence (AI) has considerably modified the search for innovative bioactive drugs and their therapeutic applications. Conventional approaches at different organizational research levels have emerged and, thus, AI associated with gene and cell therapies could supplant conventional pharmacotherapy and facilitate the diagnosis of pathologies. Using the examples of chronic pain and neuropathic disorders, which affect a large number of patients, I illustrate here how AI could generate new therapeutic approaches, why some compounds are seen as recreational drugs and others as medicinal drugs, and why, in some countries, psychedelic drugs are considered as potential therapeutic drugs but not in others., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Glioblastoma multiforme (GBM) is a deadly grade IV brain tumor. Radiation in combination with temozolomide (TMZ), the current chemotherapeutic for GBMs, only provides 12-14 months survival post diagnosis. Because GBMs are dependent on both activation of the DNA damage pathway and the endoplasmic reticulum (ER) stress response, we asked if a novel ER stress inducing agent, JLK1486, increases the efficacy of TMZ.We found that the combination of TMZ+JLK1486 resulted in decreased proliferation in a panel of adherent GBM cells lines and reduced secondary sphere formation in non-adherent and primary lines. Decreased proliferation correlated with increased cell death due to apoptosis. We found prolonged ER stress in TMZ+JLK1486 treated cells that resulted in sustained activation of the unfolded protein response (UPR) through increased levels of BiP, ATF4, and CHOP. In addition, TMZ+JLK1486 treatment caused decreased RAD51 levels, impairing DNA damage repair. Furthermore, we found delayed time to tumor doubling in TMZ+JLK1486 treated mice.Our data shows that the addition of JLK1486 to TMZ increases the efficaciousness of the treatment by decreasing proliferation and inducing cell death. We propose increased cell death is due to two factors. One, prolonged ER stress driving the expression of the pro-apoptotic transcription factor CHOP, and, second, unresolved DNA double strand breaks, due to decreased RAD51 levels. The combination of TMZ+JLK1486 is a potential novel therapeutic combination and suggests an inverse relationship between unresolved ER stress and the DNA damage response pathway., Competing Interests: None.

Objectives: To investigate anti-proliferatory activity of a selected N,N-[(8-hydroxyquinoline)methyl]-substituted benzylamine (JLK1486) on melanoma cells and to characterize its mechanism of cell population growth inhibition., Materials and Methods: In vitro cultures of B16F10 (mouse melanoma) cells were used as a model to characterize anti-proliferatory activity of JLK1486 using MTT growth assay, trypan blue viability assessment, cell cycle analysis, melanin production, β-galactosidase and acridine orange staining., Results: Proliferating B16F10 and also MeWo (human melanoma) cells were strongly growth inhibited by JLK1486, displaying IC50 values of 196 nm and 110 nm respectively. Anti-proliferatory effects were independent of cell death and were characterized by a distinct accumulation of cells in G0 /G1 phase. Tyrosinase activity and relative melanin content remained unchanged indicating that the anti-proliferatory activity was not due to phenotype differentiation. Although treated B16F10 cells stained strongly positive for senescence marker β-galactosidase, cells regained near normal proliferatory activity after removal of JLK1486. Increased acridine orange staining and presence of perinuclear vacuoles suggested induction of autophagy in B16F10 cells. Furthermore, JLK1486 pre-treatment completely abolished melphalan and antimycin A-induced apoptosis., Conclusion: JLK1486 provides a promising chemical scaffold to develop new anti-melanoma drugs or combination therapies, due to its potent inhibition of cell proliferation and induction of autophagy, at pharmacologically relevant concentrations., (© 2014 John Wiley & Sons Ltd.)

At the present time, developed countries are making a huge financial effort to support neuroscience research programs, particularly in the fields of advanced research and treatment of brain diseases and mental disorders. A part of this financial support is devoted to drug discovery programs. The purpose of this communication is to focus on the different parameters (economic, social, and scientific) allowing for the prominent belief that the discovery of new efficient drugs to treat brain disease to an increasing extent is likely to emanate from the Asian countries. A special focus on drug research and discovery in France reveals that, due to the current social context, the lack of small pharmaceutical ventures, the Mediator drug scandal, and the economic situation, the potential for discovering and developing new drugs is dramatically declining.

It was recently reported that female survivors of breast cancer have a lower risk of Alzheimer's disease (AD). This observation led to the hypothesis that there is a link between cancer and AD. This Viewpoint provides an analysis of the consequences of this hypothesis, not only from the perspective of drug discovery for new treatments, but above all, the awareness that any AD chemotherapy will require drug administration over longer periods of time before any cognitive effects are observed. Because such drugs will probably act as neuroprotective agents, slowing the progression of AD rather than curing it, they should be prescribed as soon as the first AD symptoms are detected. After a general survey of anticancer drugs that have potential therapeutic value for AD chemotherapy, new drugs that could affect specific signal transduction pathways known to be activated by anticancer drugs are presented, with the unfolding protein response pathway being one of the most relevant biological targets for new AD chemotherapeutic agents., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We report the synthesis and the β-site amyloid precursor protein cleaving enzyme-1 inhibitory properties of novel phenyl(thio)ureas bearing 2-(thio)oxothiazoline derivatives. A library of analogues was prepared according to specific synthetic schemes and the inhibitory activity was monitored using a fluorescence resonance energy transfer assay. Several analogues show potent inhibitory activities ranging between 1 and 0.01 µM and the activity is related to the NH acidity of the (thio)urea motif. Our results illustrate once again the close relationship between molecular recognition, complexation of the active site in enzymatic system, and organocatalysis utilizing explicit hydrogen bonding.

Herein I explain why I feel that new and effective Alzheimer's disease (AD) drugs cannot emerge from current developed concepts such as the amyloid pathway, or acetylcholinesterase inhibitors. The discovery of new therapeutic approaches first requires an understanding of the intimate structure of brain matter, where memory and cognition are located, and how aging alters its structure and function. Only by joining the expertise of quantum physicists and physical chemists with that of medicinal chemists, pharmacologists, biologists and medical doctors can new AD research orientations emerge., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Gliomas account for 5% to 7% of all solid cancers in adults and up to 30% of solid cancers in children; glioblastomas are the most malignant type of glioma and often have dismal prognoses. The alkylating agent temozolomide provides the greatest chemotherapeutic benefits currently available; however, glioblastoma patients cannot be cured. Novel drugs that efficiently combat glioblastomas are therefore of great interest. We report here that JLK1486, an 8-hydroxyquinoline-substituted benzylamine, could represent a novel chemical scaffold to reach this goal. Indeed, JLK1486 mediated anticancer activity in vivo (through intravenous as well as oral routes of administrations) in an orthotopic xenograft model and displayed efficiency similar to that of temozolomide. The therapeutic benefits of JLK1486 seem to relate to its ability to activate various transcription factors (including Myt1, STAT1, and peroxisome proliferator-activated receptor γ) in glioma cells. These transcription factors are implicated in the control of glioma cell proliferation, and the resultant global effect of their activation by JLK1486 was cytostatic, not cytotoxic. Thus, the current study opens the door for the development of novel compounds to combat glioblastoma using 8-hydroxyquinoline benzylamine analogs.

The importance of reactive drug metabolites in the pathogenesis of drug-induced toxicity has been investigated since the early 1950s, mainly to reveal the link between toxic metabolites and chemical carcinogenesis. This review mainly focuses on biologically active compounds, which generate reactive quinone methide (QM) intermediates either directly or after bioactivation. Several examples of anticancer drugs acting through the generation of QM electrophiles are given. The use of those drugs for chemotherapeutic purposes is also discussed. The key feature of those QM-generating drugs is their reactivity toward specific nucleophilic biological targets. Modulation of their reactivity represents a challenge for medicinal chemists because, depending on the reactivity of these QM intermediates, their interaction with critical proteins can alter the function of these key proteins and induce a wide variety of responses with functional consequences. Among the possible consequences, antiproliferative effects could be exploited for chemotherapeutic purposes. Information on how such QM-generating drugs can affect individual target proteins and their functional consequences are required to help the medicinal chemist in the design of more specific QM-generating molecules for chemotherapeutic use.

We report on the neuroprotective effects of N,N-bis-(8-hydroxyquinoline-5-yl methyl)-benzyl substituted amines (HQNBA) in a model of oxidative stress-induced nerve cell death using mouse hippocampal-derived HT22 cells. The four derivatives (JLK1472, JLK1486, JLK1522 and JLK1535) protected the HT22 cells from death at concentrations ranging from 0.1 to 1 μM. Their action is partially dependent on their ability to act as PPARγ agonists. These analogues also maintain GSH levels suggesting that they have indirect anti-oxidant effects., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

N,N-bis-(8-hydroxyquinoline-5-yl methyl)-benzyl substituted amines (HQNBA) represent a new class of compounds showing anti-cancer activity. At the chemical level the compounds were shown to react preferentially with thiol radicals which may lead to unfolded cysteine containing proteins and subsequent ER-stress. At the molecular level, treatment of U87 cells with this class of derivatives induced an over-expression of stress genes, including P53 and numerous P53 target genes. By generating shRNA U87 cell clones impaired in P53 expression we found that P53 mediates neither proliferation arrest of treated U87 cells nor over-expression of potential P53 targets. Moreover, we discovered that a representative HQNBA derivative (JLK1486) induces strong but transient senescence in U87 cells in a P53-independent manner. We demonstrate that, in contrast to its effect on established glioblastoma cell lines, JLK1486 induces extensive death of primary glioblastoma cells. We provide evidence that both caspase 3, and 7 activation, and cathepsin B and D activities account for at least part of this cell death.

A series of 33 novel divanillates and trivanillates were synthesized and found to possess promising cytostatic rather than cytotoxic properties. Several compounds under study decreased by >50% the activity of Aurora A, B, and C, and WEE1 kinase activity at concentrations <10% of their IC(50) growth inhibitory ones, accounting, at least partly, for their cytostatic effects in cancer cells and to a lesser extent in normal cells. Compounds 6b and 13c represent interesting starting points for the development of cytostatic agents to combat cancers, which are naturally resistant to pro-apoptotic stimuli, including metastatic malignancies.

A series of twenty six 8-hydroxyquinoline substituted amines, structurally related to compounds 2 and 3, were synthesized to evaluate the effects of structural changes on antitumor activity and understand their mechanism of action. The studies were performed on a wide variety of cancer cell lines within glioma and carcinoma models. The results obtained from chemical models and biological techniques such as microarrays suggest the following hypothesis that a quinone methide intermediate which does not react with DNA but which gives covalent protein thiol adducts. Micro-array analysis showed that the drugs induce the expression of a variety of stress related genes responsible for the cytotoxic and cytostatic effects in carcinoma and glioblastoma cells respectively. The described analogues could represent new promising anti-cancer candidates with specific action mechanisms, targeting accessible thiols from specific proteins and inducing potent anti-cancer effects., (Copyright 2009 Elsevier Masson SAS. All rights reserved.)

Herein we report the synthesis and neuroprotective effects of new N-alkyl-1,2,4-oxadiazolidine-3,5-diones and their corresponding synthetic intermediates, N-alkylhydroxylamines and N-1-alkyl-3-carbonyl-1-hydroxyureas, in an in vitro model of ischemia. We found five analogues that protect HT22 cells from death in the concentration range of 1-5 muM. Because members of the MAP kinase family are known to be key players in nerve cell survival and death, we characterized the role of these kinases in the neuroprotective mechanisms of the newly synthesized analogues. The results indicate that these compounds provide neuroprotection through distinct mechanisms of action.

The ganglioside GM1 has neuroprotective effects but is not of therapeutic value because of its lack of bioavailability. Thus, molecules that mimic GM1 represent a novel approach to neuroprotection. We have synthesized 19 small GM1-like analogues whose simplified structure includes a hydrophobic saturated or unsaturated moiety linked to a hydrophilic moiety. We report their neuroprotective effects in two distinct models of nerve cell death using hippocampus-derived HT22 cells. We found that several analogues protected the HT22 cells from death at concentrations ranging from 2 to 5 microM. Additional neuroprotective assays using cortical slices injured by glutamate confirmed these results. Since members of the MAP kinase family are known to be key players in nerve cell survival and death, we characterized the role of these kinases in the neuroprotective mechanisms of the GM1-like analogues. Interestingly, the results indicate that the compounds provide neuroprotection through distinct mechanisms of action.

Bis-8-hydroxyquinoline substituted benzylamines have been synthesized and screened for their antitumor activity on KB3 cell line model. Synthesis of this series of new analogues was accomplished using a one pot specific methodology which allows the synthesis of both bis- and mono-8-hydroxyquinoline substituted benzylamines. Among the synthesized compounds two compounds (4a and 5a), respectively, named JLK 1472 and JLK 1486, were particularly potent on KB3 cell line. Their CC(50) values being, respectively, 2.6 and 1.3 nM. Screened on a panel of cell lines showing various phenotype alterations, both compounds were found inactive on some cell lines such as PC3 (prostate cell line) and SF268 (neuroblastoma cell line) while highly active on other different cell lines. Mechanistic studies reveal that these two analogues did not affect tubulin and microtubules neither they exert a proteasomal inhibition effect. In contrast 4a and 5a activate specifically caspase 3/7 and not caspase 8 and 9, suggesting that their biological target should be located upstream from caspase 3/7. Moreover their cytotoxic effect is potentiated by the pro-apoptotic effects of TRAIL.

Synthesis and enzymatic evaluation of new series of N(4)-substituted piperazine naphthamide derivatives as BACE-1 inhibitors for the treatment of Alzheimer's disease are reported.

The receptor tyrosine kinase Met is crucial for the genetic program causing cancer progression and metastasis. Its nodal function during aggressiveness and resistance acquisition poses Met inhibition as an obligatory step in anti-cancer targeted therapy. Here, we applied a "Met-focussed" forward chemical biological screen to discover new agents antagonizing Met-triggered biological functions. The identified new scaffold, JLK1360, has a dual mechanism of action towards Met: it impairs Met signalling and also prevents its restoration after degradation. Docking and molecular dynamics provide evidences on the interacting mode of JLK1360 within the Met ATP-binding pocket. Moreover, computational and biochemical studies also highlighted that JLK1360 has a good degree of selectivity towards Met than other RTKs tested. Altogether, these findings demonstrate that the approach we have applied is a powerful strategy to identify compounds with combined properties towards a chosen target. Our studies show how integration of chemistry, biology and computational analysis can provide robust strategies to identify new inhibitory scaffolds suitable for further development of anti-cancer targeted therapies.

Gammadelta-T-lymphocytes contribute to innate immunity and are selectively activated by nonpeptide phosphorylated molecules (so-called phosphoantigens) produced by organisms responsible for causing a broad range of infectious diseases. gammadelta-T-cells are also activated by synthetic phosphoantigens and are cytotoxic to tumor cells. Here we report the synthesis, NMR characterization, and comparative biological evaluation of new pyrophosphate, phosphonate, and pyrophosphonate monoesters whose structures correspond to isosteric analogues and stereoisomers of the highly potent isoprenoid metabolite ( E)-1-hydroxy-2-methylbut-2-enyl 4-diphosphate called HDMAPP (hydroxy-dimethyl-allyl pyrophosphate). Both pyrophosphate and pyrophosphonate series elicit promising gammadelta-T-cell stimulatory responses in vitro, the pyrophosphonate ester (C-HDMAPP) being by far more stable than its parent pyrophosphate ester (HDMAPP) with improved ADMET properties and a similar pharmacodynamic profile based on in vivo studies in nonhuman primate. In both series, we found that E-stereoisomers are the most active derivatives and that Z-stereoisomers show very marginal bioactivity levels. These results indicate that the use of bioisosteric analogues of HDMAPP may represent promising new leads for immunotherapy.

Using SVZ (subventricular zone) tissue explants from one-day-old mice, we investigated the activity of new amino aromatic disulfide analogues and polyazamacrocycles on the migration of SVZ cells (neuroblasts). We found that among the tested analogues, non-peptidic disulfide derivative 8 significantly decreases the migration of neuroblasts from SVZ cells, and antagonized the stimulating activity of disulfide cyclic peptide 1. Discovery of compounds 1 and 8 constitutes new chemical tools which could be used to understand the mechanism of neuroblast migration during neurogenesis and eventually to identify specific genes involved in the neurogenesis.

To find new derivatives that block different virus strains entry in cells bearing specific surface receptors represent an interesting challenge for medicinal chemists. Here, we report the synthesis and the anti-HIV properties of a new series of analogues based on the introduction of quinoline moiety on various polyamine backbones, including polyazamacrocycles. Three compounds 7, 8, and 10 of this series were found active on PBMCs cells infected by HIV-1 LAV or by HIV-1 BaL, in contrast the well-known reference compound 1a (AMD 3100) was found only active on HIV-1 LAV strain.

Twenty novel beta-secretase inhibitors containing biarylpiperazine moieties belonging to naphthyl and coumarinyl series were designed for their potential use in Alzheimer's disease therapy. Enzymatic and cell-based assays have been carried out. The biological results clearly demonstrate that specific substituents located at the N(4)-position of the piperazine ring result in excellent in vitro inhibitory potency (IC(50) values ranging between 40 and 70 nM). Variable temperature NMR and modeling studies are consistent with the obtained biological data, since these studies confirmed that introduction at the N(4)-position of the piperazine ring allows productive interactions within the BACE-1 active site, which appear to be determinative for high BACE-1 inhibitory activity. These results are of particular interest since some of the new analogues belonging to the naphthyl series are almost one log more active than the best inhibitor of the similar family recently reported.

Several neurological disorders manifest symptoms that result from the degeneration and death of specific neurons. p53 is an important modulator of cell death, and its inhibition could be a therapeutic approach to several neuropathologies. Here, we report the design, synthesis, and biological evaluation of novel p53 inhibitors based on the imino-tetrahydrobenzothiazole scaffold. By performing studies on their mechanism of action, we find that cyclic analogue 4b and its open precursor 2b are more potent than pifithrin-alpha (PFT-alpha), which is known to block p53 pro-apoptotic activity in vitro and in vivo without acting on other pro-apoptotic pathways. Using spectroscopic methods, we also demonstrate that open form 2b is more stable than 4b in biological media. Compound 2b is converted into its corresponding active cyclic form through an intramolecular dehydration process and was found two log values more active in vivo than PFT-alpha. Thus, 2b can be considered as a new prodrug prototype that prevents in vivo p53-triggered cell death in several neuropathologies and possibly reduces cancer therapy side effects.

Dysfunction of copper metabolism leading to its excess or deficiency results in severe ailments. Recently, neurodegenerative disorders such as Alzheimer's disease have been associated with copper metabolism. Compounds having the ability to reduce copper levels in brain or to affect its distribution could have neuroprotective effects, mainly through a downregulation of the transcription of amyloid peptide precursor (APP). We report here the biological effect of compound 1,1'-xylyl bis-1,4,8,11-tetraaza cyclotetradecane, which specifically affects copper concentration in the brain cortex region. Its copper homeostatic activity is compared with that of clioquinol, a well-known drug, which has been recently reported as an active A beta-peptide clearance drug in vivo for Alzheimer's patients.

The protease beta-secretase plays a central role in the synthesis of pathogenic amyloid-beta in Alzheimer's disease. Here, we report a new series of analogues based on the phenyl-piperazine scaffold coupled to various heterocyclic moieties, which demonstrate improved inhibitory activities on BACE-1 (FRET assay) compared to already known naphthyl counterparts. The obtained results suggest further structural modifications to access to more potent BACE-1 inhibitors.

Starting from various cyclic or bicyclic ketones, we have synthesized novel Pifithrin-alpha analogues bearing different methyl substituted phenyl ketone groups at the N3-position of the 2-iminothiazole heterocycle. From stability studies in a biological medium as well as under specific chemical conditions, we have shown by NMR techniques that through a dehydration process, some derivatives can generate their corresponding cyclized analogues. All of the new analogues, Pifithrin-like and polycyclic dehydrated derivatives were assessed for their p53 inactivation potency by measuring survival of cortical neurons, whose death was induced by the DNA-damaging agent etoposide. Pifithrin-alpha like 2f as well as the cyclic dehydrated 6b analogue were found to be one log more potent p53 inactivators than reference compound Pft-alpha, with EC50 values ranging around 30 nM. These results support the finding that p53 inactivation by Pft-alpha analogues could be also due to the presence of the cyclic dehydrated Pft-alpha forms, generated in situ in the biological assay incubation medium.

Inhibition of gamma-secretase, one of the enzymes responsible for the cleavage of the amyloid precursor protein (APP) to produce pathogenic A beta peptides, is an attractive approach for the treatment of Alzheimer's disease. We have designed a new gamma-secretase thiazolamide inhibitor bearing a dihydronicotinoyl moiety as Redox Delivery System which allows specific delivery of the drug to the brain. Through, on the one hand, A beta peptide production measurements by specific in vitro assays (gamma-secretase Cell Free assay and Cell Based assay on HEK 293 APP transfected cells) and, on the other hand, pharmacokinetic studies on animal models, the new inhibitor shows a good pharmacokinetic profile as well as a potent gamma-secretase inhibitory activity in vitro. From the obtained results, it is expected that drug will be mainly delivered to the CNS with low diffusion in the peripheral tissues. Consequently the side effects of this gamma-secretase inhibitor on the immune cells could be reduced.

New 2-bromomethyl-8-substituted-benzo[c]chromen-6-ones have been synthesized and their bioactive properties have been evaluated on different enzymatic models: serine proteases (trypsin and alpha-chymotrypsin), HIV aspartyl protease, nitric oxide synthase and a panel of protein kinases. These new derivatives can provide upon chemical or enzymatic attack, very reactive quinonimine methide intermediates, which could be utilized for the design of enzyme inhibitors. We found that some of these new derivatives exhibit modest inhibitory activities on the studied enzyme models, but it could be improved after structure optimization.

One of the major challenges raised by HIV chemotherapy is the insurgence of viral resistance to drugs. Resistance to antiviral therapy has been observed for each of the different classes of anti-viral drugs: nucleoside reverse-transcriptase inhibitors, non-nucleoside reverse transcriptase inhibitors and protease inhibitors. The crucial question for AIDS drug research community is: Should we continue the search of new anti-HIV drugs which can overcome HIV resistance insurgence or should we consider resistance to anti-HIV drugs as a futile challenge? This review, focussed specifically on HIV antiprotease drugs, highlights the different strategies which have been developed to design new anti-protease drugs which could overcome HIV resistance, and also reviews the different classes of compounds (peptidomimetic or non-peptidomimetic) actually under investigation in order to face the problem of HIV resistance to drug.

During the coupling reaction between 3-alkoxy-7-amino-4-chloroisocoumarin and N-acyl alanine dipeptide, an unexpected deamidation reaction was observed. The proposed mechanism for this reaction involved the formation of an imide intermediate which after cleavage led to the release of amino acid moiety. The described deamidation reaction represents the first chemical model involving a non-peptidic moiety, which mimics biological and chemical deamidation processes occurring in proteins or peptides incorporating an asparagine or a glutamine residue.

New formamidine-3TC (3TC = 2',3'-dideoxy-3'-thiacytidine) analogues have been synthesized through various methods, and their antiviral activities (HIV, HBV) have been evaluated in vitro. Anti-HIV-1 in acutely infected MT-4 cells and peripheral blood monocellular cells (PBMCs) showed that compounds substituted by N,N-diarylformamidine side chains at the 4-N nucleic base position (compounds 3 and 8-11) had at least equivalent anti-HIV activity as 3TC (EC50 = 0.5 and 11.6 microM, respectively). Moreover, the newly synthesized compounds demonstrated higher anti-HBV activity (EC50 ranging from 0.01 to 0.05 microM) compared to the parent nucleoside 3TC (EC50 = 0.2 microM). It should be underlined that these new promising derivatives inhibited HIV in cells of a macrophage lineage, which are known to be cellular reservoir for HIV. These results were particularly of interest, since the antiviral activities appeared not to be mediated through the formamidine bond hydrolysis and consequently the release of free 3TC. These new analogue series were found to be highly stable to hydrolysis even after prolonged incubation in different biological media (t(1/2) ranged from 48 to 120 h). This enzymatic stability, coupled to the fact that no delay in the antiviral response was observed compared to the free 3TC antiviral response, suggest that this new N,N-diarylformamidine nucleoside series should not be considered as classical prodrugs.

In this review, we intend to highlight outstanding concepts of antiviral nucleoside prodrugs which have been developed in recent years, so as to improve the efficacy of a given antiviral drug or to overcome some drug deficiencies. Examples of antiviral carrier-linked nucleoside prodrugs or nucleoside bioprecursors are described, and their active mechanisms discussed. The described nucleoside prodrugs are classified in two structural classes: prodrugs bearing molecular modifications on the sugar moiety and prodrugs bearing molecular modifications on the nucleic base. Despite the important research work accomplished through out the world during the last few years in developing improved antiviral drugs for the treatment of HIV (human immunodeficiency virus), HBV (hepatitis B virus), HCV (hepatitis C virus), HSV (herpes simplex virus), HCMV (human cytomegalovirus), etc infections, only few nucleoside antiviral prodrugs are marketed, while promising prodrugs deriving from original concepts were developed. The most relevant concepts are discussed: (1) - pronucleotide approach allows the design of prodrugs, which by-pass the first kinase phosphorylation step; (2) - drug design based on Bodor's concept for brain delivery improved drugs and (3) - 5'-O-carbonate nucleosides and deaminase approaches, which allow active drug regeneration. Nonetheless, none of these innovative models have reached the market.

In contrast to 5'-O-carbonate 3TC derivatives (23, 24), which are clearly 3TC prodrugs, the corresponding 3TC carbamates (15-21 and 25), found to be very stable compounds with respect to enzymatic hydrolysis (cellular lysates and culture cell media) and still active on both HIV-1 and HBV infected cells, may not be 3TC prodrugs. The antiviral properties as well as the mechanism of action of 3TC analogues have been studied and evaluated.

A series of new 7-substituted-4-chloro-3-alkoxy isocoumarin derivatives were synthesized and evaluated as inhibitors of representative classes of proteases: serine protease (alpha-chymotrypsin, trypsin), cysteine protease (Caspase-3), and aspartyl protease (HIV-protease), 20S proteasome and also as inhibitors of amyloid peptide gamma-secretase-mediated production. Protease inhibition selectivity is directly related to the structure of the substituent at the 7-position of the isocoumarin nucleus. 7-Nitro-isocoumarin derivatives (4c, 4d, 4f) are potent alpha-chymotrypsin inhibitors but slightly active or inactive on HIV-protease, as well as on cysteine protease. In contrast, only derivatives bearing a free amino (5d, 5f) or a substituted amino group (6f) at the 7-position of the isocoumarin nucleus, were found weakly active or inactive on alpha-chymotrypsin, trypsin, Caspase-3 and HIV-protease, but prevent gamma-secretase-mediated production of Abeta 40/42 amyloid peptides, which is known to be involved in Alzheimer's disease. Moreover, the most active compounds on beta-amyloid peptide production [JLK6 (5d), JLK2 (5f) and JLK7 (6f)] show only weak or moderate inhibitory activity on the 20S proteasome. The obtained results suggest that the described new isocoumarin analogues could be of interest, since compounds like JLK6 (5d), JLK2 (5f) and JLK7 (6f) can be considered as possible hits for the development of new agents directed towards Alzheimer's disease.

In so much as bis-macrocyclic peptidomimetics have been recognized as high affinity substrates for HIV-1 protease, we were interested in the design and synthesis of new bis-macrocyclic bioisosteric analogues whose general structure is displayed on Fig. 2. The structures of these new analogues are characterized by the specific replacement of the methylene of the benzyl group directly attached to the N-acyl glycine residue in the original molecule 1, by its main bioisosteres, i.e. O-, S- and NH-aryl groups. Knowing that an intermediate in which an heteroatomic aryl group is directly linked to a free amine glycine residue is not stable, we developed an original synthetic pathway which involved the coupling of a specific side chain to the exocyclic carboxylic acid function, followed by an elegant oxidation-nucleophilic substitution Steglich-type reaction. Analogues 2a-d were then submitted to chemical and enzymatic hydrolysis. We demonstrated that, as expected, the specific cleavage of the exocyclic N-acyl bond led to the release of aryl moieties (phenol, thiophenol and aniline species). These chemical and enzymatic stability studies brought to light the biological potential of such macrocyclic analogues in infected cells.

We designed and synthesized a new class of serine protease inhibitors based on the oxazinone core. To this end, we first developed a short and efficient route to synthesize a new 3,4-dihydro[1,4]oxazin-2-one ring. Then we successfully synthesised the corresponding 5-bromo derivatives which have never been reported before, and demonstrated their inhibitory activities on alpha-chymotrypsin.

3-Alkoxy-7-amino-4-chloroisocoumarins have been shown to lower the beta-amyloid secretion (a major component of the senile plaques involved in Alzheimer's disease). This paper reports the characterization of new adducts resulting from the reaction between the isocoumarin synthon and different classes of amines. This study allows on the one hand, a better understanding of the biological molecular processes by which such isocoumarin derivatives may interact with enzyme nucleophiles and, on the other hand, brings out the chemical potential of these synthons to generate new polycyclic derivatives.

Starting from the chemical structure of the recent FDA-approved anti-HIV drug Amprenavir (Agenerase), a potent HIV-protease inhibitor, we have designed new series of Amprenavir bioisoteres in which the methylene group of the benzyl group was replaced by a sulfur atom. This structural modification has required an original multistep synthesis. Unfortunately, introduction of the sulfur atom abolished or drastically decreased both inhibitory activity on recombinant HIV protease and HIV infection protection on MT4 cell cultures.

This paper describes the first covalent synthesis of kappa-carrageenan-3'-azido-3'-deoxythymidine (AZT) conjugates. A succinate diester spacer was used to covalently couple AZT onto kappa-carrageenan, resulting in a tripartite prodrug. Two methods (UV and radioactive counting) are described and validated to determine the AZT loading onto the kappa-carrageenan carrier. This polymeric carrier, through its own intrinsic anti-HIV activity, is expected to act not only as a drug delivery agent but also as an anti-HIV agent. Synergism between the two drugs (kappa-carrageenan and AZT) was demonstrated when MT-4 cells were preincubated with the kappa-carrageenan-AZT conjugate prior to HIV-1-infection. A threshold of AZT loaded onto the kappa-carrageenan was required to achieve this synergistic effect. Such kappa-carrageenan-AZT conjugates could be of great therapeutic interest because these conjugates, which contain a low AZT concentration, present improved anti-HIV activities relative to free AZT. Moreover, kappa-carrageenan is a well-tolerated biopolymer, already used in the food industry.

New 5'-O-carbonate prodrugs of zidovudine (AZT) have been synthesized in order to enhance its uptake by HIV-1 infected cells, to improve its anti-HIV potency, and to optimize the intramolecular cyclic rearrangement process related to the 5'-O-(4-hydroxybutyl) carbonate moiety. Evidence of this prodrug rearrangement was confirmed by comparison of the serum half-lives of the 3'-azido-3'-deoxythymidin-5'-yl O-(4-hydroxyalkyl or -alkenyl or -alkylepoxide) carbonate prodrugs with our thermodynamic predictions. Interestingly, these 5'-O-carbonate prodrug series show increased anti-HIV potencies in conjunction with, or without, reduced cytotoxicity as compared to AZT that lead to a gain in selectivity indexes. The cytotoxicity of AZT could be reduced with these 5'-O-carbonate prodrug series by delaying the 5'-O-glucuronidation of AZT, which is one of the major limitations of AZT.

We have designed new non-peptidic potential inhibitors of gamma-secretase and examined their ability to prevent production of amyloid-beta 40 (Abeta40) and Abeta42 by human cells expressing wild-type and Swedish-mutant beta-amyloid precursor protein (betaAPP). Here we identify three such agents that markedly reduce recovery of both Abeta40 and Abeta42 produced by both cell lines, and increase that of C99 and C83, the carboxy-terminal fragments of betaAPP that are derived from beta-and alpha-secretase, respectively. Furthermore, we show that these inhibitors do not affect endoproteolysis of endogenous or overexpressed presenilins. These inhibitors are totally unable to affect the mDeltaEnotch-1 cleavage that leads to generation of the Notch intracellular domain (NICD). These represent the first non-peptidic inhibitors that are able to prevent gamma-secretase cleavage of betaAPP without affecting processing of mDeltaEnotch-1 or endoproteolysis of presenilins. The distinction between these two proteolytic events, which are both prevented by disruption of presenilin genes, indicates that although they are intimately linked with betaAPP and Notch maturation, presenilins are probably involved in the control of maturation processes upstream of enzymes that cleave gamma-secretase and Notch.